package 赛码;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
    static int sum = 1;
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        if (a%5==0){
            System.out.println(a/5);
        }else{
            ArrayList<Integer> integers = new ArrayList<Integer>();
            for (int a1=1;a1<=a;a1++){
                integers.add(a1);
            }
            function1(integers,0,a);

        }
    }
    public static void function1(ArrayList<Integer> al1,int start,int max){
        if (start+5<=max){
            if (al1.get((start+5)-1)==max) {
                System.out.println(sum);
                return ;
            }else{
                sum++;
                al1.remove(start+5-1);
                function1(al1,start+5,max);
            }
        }else{
            if (al1.get((5-(max-start)-1))==max) {
                System.out.println(sum);
                return ;
            }else{
                al1.remove(5-(max-start)-1);
                sum++;
                function1(al1,(max-start)-2,max);
            }
        }

    }
}
